Effect of solvent composition

The authors also investigated the effect of solvent composition on the retention of a series of solutes including a dispersion of silica smoke (mean particle diameter 0.002 pm). The silica smoke was used to simulate a solute of very large molecular size... 

It is seen that the curves in Figure (24) become horizontal between 40°C and 45 °C as predicted by the theory. It is also clear that there is likely source of error when exploring the effect of solvent composition on retention and selectivity. It would be important when evaluating the effect of solvent composition on selectivity to do so over a range of temperatures. This would ensure that the true effect of solvent composition on selectivity was accurately disclosed. If the evaluation were carried out at or close to the temperature where the separation ratio remains constant and independent of solvent composition, the potential advantages that could be gained from an optimized solvent mixture would never be realized. 

Fig. 22. The effect of solvent composition on the molecular weight ( ), conversion (O), and molecular weight dispersity ( ) of PaMeSt prepared using the HSi(CH3)2CH2CH2

The Effect of Solvent Composition on Retention Volume Measurement... 

Effect of Solvent Composition of Short Contact Time Conversions ... 

EFFECT OF SOLVENT COMPOSITION OF CONVERSION OF ILLINOIS 6 (BURNING STAR) COAL AT SHORT TIME (2-3 minutes, 425°C)... 

The effect of solvent composition on the solubility of polymorphs is illustrated by cimetidine [128], The onset of melting of the two forms is essentially indistinguishable, making it impossible to apply the conventional nomenclature to the labeling of the polymorphs. Form B was found to be less soluble than form A, identifying it as the more stable polymorph at room... 

Danielson LL, Gentner WA. 1970. Effect of solvent composition on inactivation of several phenyl and thio carbamate herbicides in soil. Proceedings of the Northeastern Weed Control Conference 24 308-312. 

Nakanishi, K. and Soga, N., Phase-separation in silica sol-gel system containing polyacryhc-acid. 1. Gel formation behavior and effect of solvent composition, Journal of Non-Crystalline Solids 139(1), 1-13, 1992. 

The effect of solvent composition on the retention of a series of solutes, commonly used to measure column dead volumes, was also investigated by these authors. They employed mixtures of methanol and water as the mobile phase and measured the retention volume of the same salts together with a silica gel dispersion (containing particles 0.002 micron in diameter). They also measured the retention volume of the components of the mobile phase methanol, and water. The silica dispersion was chosen to simulate a solute of very large molecular size. The results they obtained are shown in figure (2). 

Solvent amount. The amount is largely determined by the amount of nitrocellulose in the composition. Figure 3 provides an example of the effect of solvent composition and amount on density. 

Furthermore, equilibrium constants K2 for the formation of the adduct corresponding to Reaction 4 were determined by the overlap procedure in solutions containing fixed concentrations of the organic component, and the effect of solvent composition on the Hammett reaction constant p was followed. 

Method development is vastly simplified by computer simulations using commercial software. With input from a small number of real experiments, a program can predict the effects of solvent composition and temperature in isocratic or gradient separations. You can select optimum conditions in minutes with the computer instead of days in the lab. Of course, you must verify the prediction by a real experiment. Commercial software saves huge expenses in method development in industrial laboratories. 

Plattner (82) briefly examined the effects of solvent composition upon TG separations. Mixtures of acetone/methanol and acetone/acetonitrile were examined. In this work, acetone/ acetonitrile mobile phases were reported to give less complex chromatograms of TG mixtures than acetone/methanol mixtures. 

Oxidation of thio acids by tetrabutylammonium tribromide showed Michaelis-Menten-type kinetics with respect to the thio acid. The effect of solvent composition was analysed using the Grunwald-Winstein equation. A mechanism involving the formation of an intermediate complex in the pre-equilibrium and its subsequent decomposition in a slow step is proposed.129... 

Hence, the use of dual-channel detection increases the possibilities for peak assignment in optimization processes. However, complications are caused by variations in the baseline [584] and the effect of solvent composition on the UV spectrum may now become even more serious than in the case of single-channel detection. This may occur for instance if one wavelength is selected on a rising flank in the UV spectrum, and the second one on a descending flank. In any case, the selection of the two most suitable wavelengths is one of the most critical factors. Unfortunately, the wavelength selection is usually quite arbitrary. 

The Effect of Solvent Compositions on the Liquefaction Behavior of Western Subbituminous Coal... 

Different methods for the study of selective solvation have been developed [118, 120] conductance and Hittorf transference measurements [119], NMR measurements (especially the effect of solvent composition on the chemical shift of a nucleus in the solute) [106-109], and optical spectra measurements like IR absorption shifts [111] or UV/Vis absorption shifts of solvatochromic dyes in binary solvent mixtures [124, 249, 371]. Recently, the preferential solvation of ionic (tetralkylammonium salts) and neutral solutes (phenol, nitroanilines) has been studied particularly successfully by H NMR spectroscopy through the analysis of the relative intensities of intermolecular H NOESY cross-peaks [372]. 

Fig. 34. The effect of solvent composition of aqueous dioxane on the hydrolysis rate constant of p-nitrophenyl laurate. Catalyst ( ), imidazole (o), Cyclo-(D-Leu-His)...

S Zhou, M Hamburger. Effects of solvent composition on molecular ion response in electrospray mass spectrometry investigation of the ionization processes. Rapid Commun Mass Spectrom 9 1516—1521, 1995. 

Table V. Effect of Solvent Composition on Polymer Yield, Tacticity and Molecular Weight in the Polymerization of p-Chloro-a-methylstyrene with SnCl ...

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